A phenomenon in which the temperature of an urban area becomes higher than the temperatures of the surrounding areas is called “heat island phenomenon.”
In recent years, the heat island phenomenon in cities has been said to be a cause of worsening urban environments in conjunction with the influences of global warming. It is said that in the last 100 years, the global average temperature has risen by 0.6° C., while in Japan the temperatures in large cities have risen by 2.4° C., and the temperature in Tokyo has risen by 2.9° C.
Clusters of high-rise buildings constructed of various materials, exhaust heat produced by automobile engines and the like, influences of road paving with asphalt, and the like, which represent urban-specific environmental structure, are regarded to be accelerating the heat storage effect of the heat island.
There is still much uncertainty about the heat storage mechanism in such urban-specific environmental structure. In order to explore effective measures against the heat island phenomenon, there is a demand for clarifying the heat storage mechanism in the urban-specific environmental structure.
In clarifying the urban heat storage mechanism, it is essential to practically deal with radiation processes such as a radiation process between buildings and a radiation process between a building and a road, as well as to identify heat sources, such as artificial heat release, and to perform quantification thereof.
Conventionally, there have been models built for clarifying, in a city model, the heat storage mechanism caused by the radiation. Examples of the main methods of the conventional models include the following.
(1) A single building or a plurality of buildings having simple contours are set as subjects.
(2) A plurality of buildings having continuous and uniform contours are set as subjects.
(3) A canopy model representing vertical two-dimensional radiation processes between the ground surface and the atmosphere is used.
(4) The average amount of radiation is determined based on a statistical average value.
In those methods, in order to keep the calculation cost lower, the contours, the arrangement, and the like of real three-dimensional buildings are simplified or subjected to smoothing. Accordingly, those methods do not correspond precisely to the three-dimensional contours of real buildings. For this reason, those conventional models may result in divergences from the real thermal radiation processes.
Non-patent Document 1: Taiki Sato, Shuzo Murakami, Ryozo Ooka, Yoichi Kawamoto: “ESTIMATION OF STANDARD EFFECTIVE TEMPERATURE (SET) AT THE PEDESTRIAN AREA BASED ON NUMERICAL CLIMATE MODEL”, Summaries of Technical Papers of Annual Convention, Architectural Institute of Japan, 2005.
Non-patent Document 2: Hiroyuki Kusaka, Fujio Kimura: “MECHANISM FOR NOCTURNAL HOT AND HUMID CONDITIONS USING AN URBAN WEATHER MODEL”, Tenki, Japan Weather Association, 2004, No. 51 (2), pp. 95-98.
Non-patent Document 3: Aya Hagishima, Jun Tanimoto, Tadahisa Katayama, Kenji Ohara: “AN ORGANIC ANALYSIS FOR QUANTITATIVE ESTIMATION OF HEAT ISLAND BY THE REVISED ARCHITECTURE-URBAN-SOIL-SIMULTANEOUS SIMULATION MODEL (AUSSSM): PART 1 THEORETICAL FRAME OF THE MODEL AND RESULTS OF STANDARD SOLUTION”, Journal of Architecture, Planning and Environmental Engineering, Architectural Institute of Japan, 2001, No. 550, pp. 79-86.
Non-patent Document 4: Aya Hagishima, Jun Tanimoto, Tadahisa Katayama, Kenji Ohara: “AN ORGANIC ANALYSIS FOR QUANTITATIVE ESTIMATION OF HEAT ISLAND BY THE REVISED ARCHITECTURE-URBAN-SOIL-SIMULTANEOUS SIMULATION MODEL (AUSSSM): PART 2 QUANTITATIVE ANALYSIS BASED ON A SERIES OF NUMERICAL EXPERIMENTS”, Journal of Architecture, Planning and Environmental Engineering, Architectural Institute of Japan, 2002, No. 553, pp. 91-98.
Non-patent Document 5: Aya Hagishima, Jun Tanimoto, Fumihiro Asano: “AN ORGANIC ANALYSIS FOR QUANTITATIVE ESTIMATION OF HEAT ISLAND BY THE REVISED ARCHITECTURE-URBAN-SOIL-SIMULTANEOUS SIMULATION MODEL (AUSSSM): PART 3 SENSITIVITY ANALYSIS ON FACTORS OF URBAN HEAT ISLAND UNDER VARIOUS METEOROLOGICAL REGIONS”, Journal of Environmental Engineering, Architectural Institute of Japan, 2006, No. 601, pp. 43-50.